Senator McCain has so far failed to respond, but Senator Obama said: “I’ll be a President that stands up for American families – all of them.”

“The desire to build a life with a loved one, to provide for a family and to have children who will grow and thrive — these are desires that all people share, regardless of race, sex, religion, sexual orientation or gender identity,” he wrote.

“My own experience has taught me this lesson well. I was born to a single mother, my devoted grandparents helped raise me, and then I married the woman of my dreams and had two beautiful daughters.

“The love that has blessed each of those households has been strong and sure, and I know that millions of families across this nation share the same blessings.

“We also have to do more to support and strengthen LGBT families.

“Because equality in relationship, family, and adoption rights is not some abstract principle; it’s about whether millions of LGBT Americans can finally live lives marked by dignity and freedom.”

Senator Obama listed more funding for after-school programmes, the abolition of the federal ban on same-sex marriage, an end to discrimination against LGBT families and “equal treatment in our family and adoption laws” as goals for his administration.

The FEC praised the candidate and pointed out that according to the 2000 census, more than 75% of American households “differ from the paradigm of a married, heterosexual couple raising their biological children.”

Ms Chrisler stated in her letter to the candidates:

“Thirty-seven percent of parent households with children in the home are not headed by married,
heterosexual couples.

“Since 1940, grandparents have been the primary caregivers (without biological parents in the home) for approximately 2 percent of all children in this country, some 1.6 million children today.

“Forty percent of all children will likely be raised by unmarried partners living together for a portion of their lives.

“Lesbian and gay parents are raising four percent of all adopted children in the United States, as well as three percent of all children in foster care.

“Until grandmothers and grandfathers can easily access the government benefits intended to keep their grandchildren healthy and safe; until lesbian, gay, bisexual and transgender parents can have their relationships universally and unquestionably recognised; until unmarried parents can access benefits without penalty or derision, we will not be doing justice by the millions of American families that do not fit a small minority’s notion of what a”real” family is.”

Senator McCain’s comments about gay adoption were seized upon by LGBT rights advocates as evidence that he is hostile to their community.

“We are disappointed and saddened that a public leader who is himself an adoptive father would deny the children in America’s foster care system the opportunity to thrive as part of a welcoming family.

“In a country where more than 125,000 children are waiting for foster parents, Senator McCain would deny loving homes to children who desperately need them simply because of an outdated prejudice about what a family may look like.”

In the wake of such criticism after his New York Times interview last month, the McCain campaign’s Director of Communications, Jill Hazelbaker, made the following clarification:

“McCain could have been clearer in the interview in stating that his position on gay adoption is that it is a state issue, just as he made it clear in the interview that marriage is a state issue.

“He was not endorsing any federal legislation.

“McCain’s expressed his personal preference for children to be raised by a mother and a father wherever possible.

“However, as an adoptive father himself, McCain believes children deserve loving and caring home environments, and he recognises that there are many abandoned children who have yet to find homes.

“McCain believes that in those situations that caring parental figures are better for the child than the alternative.”